Rectangular Prism Surface Area Calculator

Our Rectangular Prism Surface Area Calculator helps you quickly find the total area of all the faces of any rectangular box. Just enter the length, width, and height, and we'll do the math for you.

Length (l)

Enter the length of the prism (e.g., 10 cm)

Width (w)

Enter the width of the prism (e.g., 5 cm)

Height (h)

Enter the height of the prism (e.g., 3 cm)

Please enter a valid positive number for the length.

How it works

Our Rectangular Prism Surface Area Calculator helps you quickly find the total area of all the faces of any rectangular box. Just enter the length, width, and height, and we'll do the math for you.

The Formula

The surface area (SA) of a rectangular prism is found by adding the areas of all six faces. Since opposite faces are identical, the formula simplifies to: SA = 2(lw + lh + wh) Where:
• l = length
• w = width
• h = height

Worked Example

Example: A Cereal Box
Imagine a standard cereal box that is 20 cm long, 8 cm wide, and 30 cm high. To find its surface area, you'd calculate: SA = 2 * ( (20 * 8) + (20 * 30) + (8 * 30) ) SA = 2 * ( 160 + 600 + 240 ) SA = 2 * ( 1000 ) SA = 2000 cm² Our calculator will show you this result instantly!

Tips, Assumptions & Limitations

Ensure all measurements (length, width, height) are in the same unit before calculating.
The surface area is always expressed in square units (e.g., cm², m², ft²).
This calculator is perfect for packaging design, painting projects, or school assignments.

FAQ

The surface area of a rectangular prism is the total area of all its faces. Imagine unfolding a box into a flat shape; the surface area is the total area of that flat shape. It's measured in square units like cm² or ft².

You can calculate it using the formula SA = 2(lw + lh + wh), where 'l' is length, 'w' is width, and 'h' is height. Our calculator does this for you automatically once you provide these three measurements.

Yes, a cube is a special type of rectangular prism where all sides (length, width, and height) are equal. Simply enter the same value for length, width, and height into the calculator to find the surface area of a cube.